Abdeljawad, Thabet; Baleanu, Dumitru
(Springer International Publishing AG, 2017-03-09)
We prove that if the Caputo-Fabrizio nabla fractional difference operator ((CFR) (a-1)del(alpha) y)(t) of order 0 < alpha <= 1 and starting at a -1 is positive for t = a, a + 1,..., then y(t) is a-increasing. Conversely, ...